Control system for steam jet refrigerating mechanism



May 16, 1939. J. E. HAINES 2,153,059

CONTROL SYSTEM FOR STEAM JET REFRIGERATING MECHANISM Filed Jan. 8, 1936 2 Sheets-Sheet l May 16, 1939. J. E. HAINES CONTROL SYSTEM FQR STEAM. JET R EFRIGERATING MECHANISM Filed Jan. 8, 1936 2 Sheets-Sheet 2 QDN Patented May 16, 1939 UNITED STATES CONTROL SYSTEM non STEAM JET REFRIGERATING \MECHANISM John E. Haines, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company,

Minneapolis, ware Minn., a. corporation of Dela- Application January 8, 1936, Serial No. 58,121

, 17 Claims.

This invention relates to control systems for refrigerating mechanisms and particularly to that type of refrigerating mechanism comprising evaporators, ejectors and condensers.

An object of this invention is to provide a control system for such a refrigerating mechanism whereby the refrigerating mechanism may be readily placed in operation upon a call for cooling, and whereby it may be maintained in operation in an extremely eflicient manner.

More specifically, an object of this invention is to provide a control system for a refrigerating mechanism of the type specified wherein high pressure steam is admitted to the ejector for a predetermined interval of time upon acall'for cooling to place the refrigerating mechanism in operation and then reduced pressure steam is admitted to the ejector to maintain the refrigerating mechanism in operation in an efficient manner.

Another object of this invention is to provide a control system for a refrigerating mechanism of the type specified wherein the supply of steam to the ejector is maintained at a substantially constant pressure by a pressure regulating means, and wherein the pressure of the steam admitted to the ejector may be varied in accordance with the condition of the condenser to maintain a constant pressure drop acrossthe ejector regardless of the vacuum existing within the condenser whereby a constant vaccum is maintained in theevaporator.

Another object of this invention is to provide a control system for a refrigerating mechanism and starting and running nozzles wherein steam at high pressure is admitted to the starting nozzles to place the refrigerating mechanism in operation, steam'is admitted to the running nozzles at high pressure to aid in placing the refrigerating mechanism in operation and steam is admitted to the running nozzles at a reduced pressure,

preferably a constant pressure, to maintain therator will be produced more readily than if this 55 steam were allowed to back up into the evaporahaving an evaporator, anejector, a'condenser' tor whereby the refrigerating mechanism may be rapidly placed in condition for operation.

A further object of this invention is to provide a refrigerating mechanism having a primary evaporator and ejector and a secondary evaporator and ejector, both communicating with a common condenser, the primary evaporator and ejector being maintained in operation at all times and the secondary evaporatorand ejector being placed in operation only when the load on the refrigerating mechanism becomes sufficiently great that it can not be handled by the primary evaporator and ejector, along with control means for placing the secondary evaporator and ejector in operation automatically in accordance with the increased load and for preventing communication between the primary and secondary evaporators and the primary and secondary ejectors, respectivelyywhen the secondary evaporator and ejector are being placed in operation.

Still another object of this invention is to provide a program switch operated in response to a demand for cooling for performing various sequences of operation more clearly set forth in the annexed specification.

Other objects and advantages will become apparent to those skilled in the art upon reference to the accompanying specification, claims anddrawings, in which drawings:

Figure 1 is a schematic illustration of a steam jet refrigerating mechanism having a main evaporator and a secondary evaporator with thecontrol system of my invention applied thereto;

and

Figure 2 is a wiring diagram showing the manner of operation of my control system.

Referring now to Figure 1, the main evaporator is designated at [0 and is provided with sprays H for spraying the cooling fluid into the evaporator I 0. The cooling fluid is delivered to the sprays II from some point of use (not shown) through a pipe l2 under the control of a valve l3 which is operated in accordance with the liquid level of the cooling fluid within the evaporator III by a liquid level responsive controller H. The liquid level responsive controller l4 maintains a constant amount of cooling fluid within the evaporator III. The chilled cooling fluid is drawn from the main evaporator I0 through a pipe ,and delivered to a point of use for the purpose of cooling.

The upper surface of the evaporator It! opens into a valve [6 having a gate IT. The gate I! may be oper 11, ed by a hydraulic motor it! under the control H a four-way-valve l9 which admits and exhausts liquid to and from the hydraulic motor I8. The valve I9 is moved from one extreme position to the other extreme position by an electric motor designated at 20.

Mounted on the top of the valve l6 and in communication therewith is a nozzle box 2| having starting nozzles 22 and running nozzles 23. Steam is supplied to the starting nozzles- 22 through a pipe 24 from a steam header 25 under the control of a manually operated valve 26. Steam is supplied to the running nozzles 23 through a pipe 21 from a steam header 28 under the control of a manually operated valve 29. The pressure of the steam within the second steam header 28 is regulated by means of a pressure regulating valve 30 and the upstream side of this valve 30 may be connected into the high pressure steam header 25 as by means of a pipe 3|.

The nozzle box 2| is connected by a main ejector 32 to a condenser designated at 33. The condenser 33 may contain the usual condenser tubes 34. The condensed steam conveyed to the condenser 33 by the main ejector 32 may accumulate in a condensate chamber 36 and may be drawn off therefrom through a pipe 31 by means of a condensate or vacuum pump (not shown). The condenser 33 may also be connected to first and second stage ejectors for the purpose of purging the condenser of air by means of a pipe 38 in the manner well known in the art. Condensing water is admitted to the condenser by means of a pipe 39 and is discharged therefrom by means of a pipe 40.

The main steam jet ejector refrigerating mechanism so far described may be placed in operation by placing a vacuum on the condenser 33 and by opening the steam valve 25 for admitting high pressure steam to the starting nozzles 22 whereby a vacuum is created within the main evaporator II! to cause flashing into steam of a portion of the returning cooling fluid flowing from the sprays l I in the evaporator III. This chills the cooling fluid within the evaporator ID in a manner well known in the art. After the main refrigerating mechanism is thus placed in operation the steam valve 29 is opened to admit steam at a regulated pressure to the running nozzles 23 and the valve 26 is closed. This allows the refrigerating mechanism to be maintained in operation by the pressure regulated steam coming from .the regulated pressure steam header 28. The main steam jet refrigerating mechanism is preferably maintained in operation at all times.

The secondary evaporator is designated at 42 and may likewise contain sprays 43 which receive cooling fluid from a point of use through a pipe 44 under the control of a valve 45 which valve is operated in accordance with the liquid level in the evaporator 42 by a liquid level responsive controller 46 to maintain a constant liquid level within the evaporator 42. A portion of the cooling fluid is flashed into steam'in order to chill the. remainder of the cooling fluid in the manner pointed out with reference to the .evaporator l0 and the chilled cooling fluid is drawn from the secondary evaporator 42 through a pipe 41 and delivered to a point of use for the purpose of cooling. The evaporator 42 Opens into a valve 48 having a gate 49 which is also operated by a hydraulic motor designated at 50. Liquid is admitted to,and exhausted from the hydraulic motor 58 by means of a four-way valve 5| which is spring-biased to one extreme position and which is moved to the other extreme position upon energization of a solenoid designated at 52.

The valve 48 in turn opens into a nozzle box 53 having starting nozzles 54 and running nozzles 55. Steam is supplied to the starting nozzles 54 from the high pressure steam header 25 under the control of a valve 58. The valve is moved to either open or closed positions by means of an electric motor 59. Steam at a-regulated pressure is admitted to the running nozzles 55 from the regulated pressure steam header 28 under the control of a valve 56 which is moved to either open or closed position By means of an electric motor 51.

The nozzle box 53 connects with a secondary ejector 60 which in turn is connected into the condenser 33 by means of a conduit 8|. The secondary steam jet ejector refrigerating mechanism is placed in operation in substantially the same manner as the main steam jet ejector refrigerating mechanism by admitting steam to the starting nozzles 54 and then by admitting pressure regulated steam to the running nozzles 55.

The valves Sand 48 associated with evaporators I0 and 42 respectively are provided for closing off the evaporators l0 and 42 from the nozzle boxes 2| and 53, respectively, when the secondary steam jet refrigerating mechanism is to be placed in operation. The valves I6 and 48 are closed at this time to prevent the backing up of steam into the evaporators Ill and 42 in order to expedite the placing of the secondary refrigerating mechanism into operation.

The pressure regulating valve 30 is shown to be operated by a conventional hydraulically operated regulating device and may comprise a lever 63 secured to the valve stem of the pressure regulating valve 38 and a. chain or cable 64 connecting the lever 63 to a piston rod 65 of a hydraulic motor 66. The hydraulic motor 66 is controlled by a valve located in a valve chest 61 which is operated in accordance with the steam pressure existing within the regulated pressure steam header 28, the connection to this heater 28 being made by a pipe 68. The hydraulic regulating device, of course, is provided with the usual follow-up device whereby the pressure regulating valve 30 may be positioned in accordance with the pressure existing within the header 28 to maintain constant pressures therein. The hydraulically operated regulating device may be adjusted by means of a lever 69 which is connected by a chain or cable 10 to a crank H which is variably positioned by a proportioning motor 12. The lever 69 may adjust the hydraulically operated regulating device in any suitable manner and specifically it may adjust the tension of the spring of the pressure responsive device contained within the valve chest 61 which counteracts the pressures in the header 28 in a manner well known in the art.

This invention contemplates the use of a temperature responsive controller 14 of the variable resistance type which is connected by a capillary tube 15 to a bulb 16 located in the condensate 36 of the condenser 33. The controller 14, therefore, responds to changes in temperature of the condensate within the condenser 33, it being known that the condensate temperature increases as the condenser vacuum decreases.

It is also Within the contemplation of this invention to utilize a temperature responsive controller 11 which is connected by a capillary tube 78 to a bulb 19 located within the main evapo-. 'rator l0. Therefore, the controller 11 respondstroller 80, therefore, responds also to changes in temperature of the chilled cooling fluid in the main evaporator I0.

Located at some convenient point is a panel board designated at 83 and on this panel board 83 are mounted a program switch 84 operated by a motor 85, a proportioning relay 06, two oil and on type relays 81 and 88, a variable resistance range controller 89, a variable resistance differential controller 90 and a signal or alarm 9I. The various motor switches, solenoids, relays, temperature responsive devices, variable resistances and alarms are all suitably connected together by conduits as shown in Figure 1. Electric power is supplied to the panel board 83 by means of a conduit 92 leading from some source of power (not shown).

The manner in which the various elements of the control system are connected together and the construction of these control elements is shown diagrammatically in Figure 2. The temperature responsive controller 1! which responds to the temperature of the cooling fluid in the main evaporator I0 may comprise a bellows 94 for operating a pivoted lever 95 which carries a double-ended mercury switch 96 having high temperature contacts at the left end thereof and low temperature contacts at the right end there- The temperature responsive device I4 which has the bulb I6 responding to the temperature of the condensate within the condenser 33 may comprise a bellows 91 for operating a slider 98 with respect to a potentiometer coil 99. Upon an increase in temperature of the condensate the slider 98 is moved upwardly with respect to the potentiometer coil 99 in the direction indicated by the character H, and upon a decrease in temperature the slider 98 is moved downwardly with respect to the potentiometer coil 99 in the direction indicated by the character C.

The temperature responsive device 80 which also responds to the temperature of the cooling fluid within the evaporator I0 may comprise a bellows I00 for operating a pivoted lever IOI which carries a mercury switch I02, the arrangement being such that when the temperature of the cooling fluid located within the evaporator I0 decreases to a predetermined low value the mercury switch is tilted to a' circuit making position opposite to that shown in Figure 2.

The valve 56 which controls the supply of regulated steam to the secondary ejector 60 may be operated by a pitman I03 connected to a gearcontacts Ill and 5- When the valve 56 Is in either its extreme open or extreme closed positions the switch arm H0 is maintained out of engagement with the contact III, but when the valve 56 is in any position other than these extreme positions the switch arm H0 is held in engagement with the contact III. The cam I09, the switch arm I I0 and the contact III form a maintaining switch, the action 'of which will be pointed out more fully hereafter. The switch arm H3 is maintained in engagement with the contact I I4 when the valve 56 is in a closed position and with the contact II5 when the valve 56 is in an open position. The cam II2, the switch arm H3 and the contacts H4 and H5 form a selecting switch the operation of which will also be pointed out more fully hereafter.

The valve 58 which controls the supply of high pressure steam to the secondary ejector 50 may be operated by a pitman II'I connected to a gear II8 mounted on a shaft II9 of the motor 59. The gear H8 is driven through a reduction gear train generally designated at I by a motor rotor I2I upon the energization of the field winding I22. The motor 59 also includes a. maintaining switch mechanism which comprises a cam I23, a switch arm I24 and a contact I25 and a selecting switch mechanism which comprises a cam I26, a switch arm I21 and contacts I28 and I29.

The motor 20 which operates the four-way valve I9 which in turn controls the valve I6 associated with the main evaporator I0 may operate the valve I9 through a pitman I3I connected to a gear I32 mounted on a shaft I33. The gear I32 may be driven through a reduction gear train I34 by a motor rotor I35 upon the energization of a field winding I36. The motor 20 also includes a. maintaining switch mechanism which comprisesa cam I31, a switch arm I38 and a contact I39 and a selecting switch mechanism which comprises a cam I40, a switch arm MI and contacts I42 and I43. At this point it will be noted that the valves 55 and 58 are in a closed position and the four-way valve I9 is in an open position.

The solenoid 52 for operating the four-way valve 5I which controls the operation of the valve 48 associated with the secondary evaporator 42 may comprise a coil I for controlling the operation of an armature I 46. The valve 5| is in a closed position, being biased to this closed position by a compression spring I4I. of the coil I45 the compression spring I4! is compressed and the four-way valve 5| is moved to an open position.

The proportioning motor I2 which operates the crank II for adjusting the setting of the hydraulically operated pressure regulating valve may comprise a shaft I49 upon which the crank II is mounted. The shaft I49 carries a gear I50 which is driven through a reduction gear train I5I- by motor rotors I52 and I53. Themotor rotors I52 and I53 are placed in operation by energization of field windings I 54 and I55, respectively, the arrangement being such that when the field winding I54 is energized the motor I2 is operated to move the crank II downwardly to raise the set-- ting of the hydraulically operated pressure regulating device whereby the steam pressure within the regulated pressure header 28 is increased. When the field winding I55 is energized the crank II is moved upwardly to lower the setting of the pressure regulating device to decrease the steam pressure existing in the header 28. The shaft I49 also carries a bevelled gear I56 which meshes with Upon energization till a bevelled gear I51 which in turn carries an abutment member I58. The abutment member I58 carries a slider I59 which cooperates with a balancing potentiometer 0011- I60. The abutment member I58 also carries spaced fingers I6I and I62 which are adapted to engage contacts I63 and I84 at either extreme position of the motor 12. The contacts -I63 and I65 form a limit switch for preventing movement of the motor 12 beyond one extreme position upon energization of the field winding I54 and the contacts I64 and I66 form a limit switch for preventing movement of the motor 12 beyond the other extreme position upon the energization of the fieldwinding This invention-contemplates the use of a program switch designated at 64 for obtaining a predetermined sequence of operation. The program switch is shown to comprise an outer track I68.

track I68 has a series of spaced conducting portions I10, "I, I12, I13, I14 and I15, preferably located in the positions shown in Figure 2. The

tracks I68 and I69 are bridged by a. slider I16 which is carried by a bevelled gear I11 and the bevelled gear I11 meshes with another bevelled gear I18 mounted on a shaft I19. The shaft I19 also carries another bevelled gear I8I which engages with a second bevelled gear I82. Upon rotation of the bevelled gear I82 the slider I16 is rotated in a clockwise direction as indicated by the arrow to first cause contact between the conductor I and the track I69, then between the conductor HI and the track I69 and so on until 180 of rotation is completed. When the slider I16 has been moved through-180 it comes to rest in a position bridging the conductor I14 and the track I69. Upon the next 180 of rotation the conductor I16 bridges the conductor I and the track I69 and comes to rest at the position shown in Figure 2.

The slider I16 is driven through these 180 cycles by the motor 85 which comprises a shaft I83 upon which is mounted the bevelled gear I82. The shaft I83 also carries a gear I84 which is driven through a reduction gear train I85 by a motor rotor I86 upon energization of a field winding I81. The shaft I83 alsocarries a cam I88 which operates a slider I89 with respect to a contact I90 forming a maintaining switching mechanism, the operation of which will be more clearly pointed out hereafter. The shaft I83 also carries a cam I9I which operates a switch arm I92 with respect to spaced contacts I93 and I94 which form a selecting switch, the operation of which will be more clearly pointed out hereafter. The reduction gear train I85 is so selected that the slider I16 will be rotated at a comparatively slow rate of speed through its 180 movements.

The proportioning relay 86 which is mounted on the panel board 83 is shown to comprise a step-down transformer I96 having a primary I91 and a secondary I98. One end of the secondary I98 is connected by wires I99, 200 and I arrangement being such that when thecoil 201 is energized more than the coil 202 the switch arm 209 is moved into engagement with the contact 2H and when the coil 202 is energized more than the coil 201 the switch arm 209 is moved into engagement with the contact 2I0. When the coils 202 and 201 are equally energized the switch arm 209 is maintained in a mid position as shown in the drawings. The contact 2I0 is connected by a wire 2I2 to a small number of turns of the coil 202 and the contact 2 is connected by a wire 2I3 to a small number of turns of the coil 201. The switch arm 209 is connected by a wire 2 to the junction of coils 203 and 208. The coils 203 and 208 operate a switch arm 2I5 with respect to contacts M5 and 2". When the coil 203 is energized more than the coil 208 the switch arm 2I5 is moved into .engagement with the contact 2I6 and when the coil 208 is energized more than the coil 203 the switch arm H6 is moved into engagement with the contact 2". When the coils 203 and 208 are equally energized the switch arm 2I5 is maintained in the mid position as shown in the drawings.

The relay 81 mounted on the panel board 83 is shown to comprise a relay coil 2I9 for operating switch arms 220 and 22I, the arrangement being such that when the relay coil 2I9 is energized the switch arms 220 and 22I are moved into engagement with contacts 222 and 223, respectively, and when the relay coil 2I9 is de- -energized the switch arms 220 and HI are moved.

into engagement with contacts 224 and 225 by means of springs, gravity or other means (not shown).

The relay 88 mounted on the panel board 83 is shown to comprise a relay coil 221 for operating a switch arm 228, the arrangement being such that when the relay coil 221 is deenergized the switch arm 228 is maintained in engagemnt with a contact 229 by means of springs, gravity or other means (not shown) and when the relay coil 221 is energized the switch arm 228 is moved out of engagement with the contact 229. The range adjusting device 89 also mounted on the panel board 83 is shown to comprise resistances 230 and 23I which are engaged by sliders 232 and 233, respectively, the sliders 232 and 233 being moved simultaneously either to the right or to the left by manual manipulation thereof. The differential adjusting mechanism 90 also mounted on the panel board 83 is shown to comprise a resistance 234 engaged by a slider 235, the slider-235 being manually moved with respect to the resistance 234. Line wires leading from some source of power (not shown) are designated at 231 and 238. The line wire 231 is connected by wires 239 and 240 to the left-hand end of the primary I91 of the relay 86 and the right-hand end thereof is connected by wires 2 and 242 to the other line wire 238.

The left-hand end of the coil 202 of the relay 86 is connected by wire 200, protective resistance 243, wires 244, 245 and 246, slider 232, resistance 230 and wire 241 to the upper end of the potentiometer coil 99 of the temperature responsive controller 14. The junction of wires 244 and 245 is connected by a wire 248 to the right-hand 'end of the balancing potentiometer I60, and the junction of wires 245 and 246 is connected by a wire 249 to the contact 223 of the relay 81. The right-hand end of the coil 201 is connected by a wire 205, a protective resistance 250 and wire I to the left-hand end of the balancing potentiometer coil I60 and by a wire 252, slider 233, resistance 23I and wire 253 to the lower end of the potentiometer coil 99 of the controller 14.

The junction of the coils 202 and 201 is connected by wires 254 and 251, resistance 234, slider 235 and wire 258 to the slider I59 associated with the balancing potentiometer coil I60. The junction of the coils 202 and 201 is also connected by the wire 254 and a wire 255 to the switch arm 22I of the relay 81. The contact 225 is connected by a wire 256' to the slider 98 of the controller 14.

From the above wiring connections of the relay 86 and the connections between the relay 86, the balancing potentiometer of the motor 12 and the potentiometer of the controller 14, it will be seen that the left-hand ends of the secondary and the coil 202 are connected to the right-hand end of the balancing potentiometer I60 and the upper end of the potentiometer coil 99, and that the right-hand ends of the secondary I98 and the coil 201 are connected to the left-hand end of the balancing potentiometer coil I60 and the lower end of the potentometer coil 99. It is also seen that the junction of the coils 202 and 201 is connected to the slider I59 of the balancing potentiometer and the slider 98 of the controller 14. The secondary l98, the coils 202 and 201, the balancing potentiometer of the motor 12 and the potentiometer of the controller 14, therefore, are all connected in parallel.

The switch arm 2I5 controlled by the coils 203 and 208 is connected by wires 260 and 239 to the line wire 231. The contact 2I6 associated therewith is connected by a wire 26I to the limit switch contact I65 and the limit switch contact I63 is connected by a wire 262 to one end of the field winding I54. The contact 2I1 also associated with the switch arm 2I5 is connected by a wire 263 to the limit switch contact ,I64 and the limit switch contact I66 is connected bya wire 264 to one end of the field winding I55. The other ends of the field windings I54 and I are connected together and are connected by wires 265 and 242 to the line wire 238.

The temperature responsive controller 14 and the proportioning motor 12 which adjusts the setting of the hydraulically operated -pressure regulating valve 30 is utilized in this invention to maintain a constant pressure drop across the orifice of the main steam jet ejector 32 at all times and the secondary steam jet ejector when it is in operation. As the vacuum in the condenser 33 decreases the temperatureof the condensate therein increases and this increase in temperature is utilized to increase the pressure setting of the pressure regulatorwhereby steam at a higher pressure is admitted to the running nozzles 23 and 55 to increase the pressure thereat whereby the pressure drop across the orifices 32 and 60 is maintained constant.

The specific manner in. which this mode of operation is brought about is clearly set forth in. Figure 2. Upon an increase in temperature of the condensate in the evaporator 33 the bellows 91 expands to move the slider 98 upwardly with respect to the potentiometer coil 99. This upward movement causes partial short-circuiting of the coil 202 through a circuit from the inner end of the coil 202 through wires 254, 255, switch arm 22I, contact 225, wire 256, slider 98, the upper portion of the potentiometer coil 99, wire 241, resistance 230, slider 232, wires 246, 245 and 244, protective resistance 243 and wire 200 back to the other end of the coil 202. Due to the parallel relationship pointed out above, this partial short circuiting of the coil 202 decreases the energizationthereof and increases theenergization of the coil 201. Due to this unbalanced relationship of the coils 202 and 201 the switch arm 209 is moved into engagement with the contact 2 which completes a short-circuit for the coil 208 from the inner end of the coil 208, through wire 2I4, switch arm 209, contact 2, wire 2I3, a small number of turns of the coil 201 and wires 205 and 206 back to the other end of the coil 208. This short-circuiting of the coil 208 decreases the energization thereof and increases the energization of the coil 203. Due to this unbalanced relationship of the coils 203 and 208 the switch arm 2I5 is moved into engagement with the contact 2I6 to complete a circuit from the line wire 231, through wires 239 and 260, switch arm 2I5, contact 2I6, wire 26I, limit switch contacts I and I63, wire 262, field winding I54 and wires 265 and 242 back to the other line wire 238. Completion of this circuit causes energization of the field winding I54 to move the crank 1I downwardly to raise the pressure setting of the hydraulically operated presrespect to the balancing potentiometer coil I60 and this left-hand movement causes a partial short-circuit through the coil 201, the circuit being completed from the inner end of the coil 201, through wire 254 and 251, resistance 234, slider 235, wire 258, slider I59, the left-hand portion of the balancing potentiometer coil I60, wire 25I, protective resistance 250, and wire 205 back to the other end of the coil 201. This partial shortcircuiting of the coil 201 decreases the energization thereof and increases the energization of the coil 202, it being remembered that the coil 201 was energized more than the coil 202 by the'upward movement of the slider 98 with respect to the potentiometer coil 99. When the slider I59 has moved sufliciently far to the left with respect to the balancing potentiometer coil I 60 so as to cause re-balancing of the coils 202 and 201, the switch arm 209 is moved out of engagement with the contact 2 to the mid-position shown in the drawing thus breaking the shortcircuit through the coil 208. The coils 203 and 208 thereupon become equally energized and the switch arm 2I5 is moved out of engagement with the contact 2I6 to the mid-position shown in the drawings. This causes breaking of the circuitthrough the field winding I54 to prevent further downward movement of the crank 1I whereby the pressure regulator 30 is maintained in a. position to deliver steam at the proper regulated pressure to the running nozzles 23 and 56 I in accordance with the temperature of the condensate in the condenser 33.

Upon a drop in temperature of the condensate slider 98, the lower end of the potentiometer coil 99, wire 253, resistance 23I, slider 233, wires 252 and 25I, protective resistance 250 and wire 205 back to the outer end of the coil 201. This decreases the energization of the coil 201 and increases the energization of the coil 202 and due to this unbalanced relationship of the coils 202 and 201 the switch arm 209 is moved into engagement with the contact 2I0. This completes a short-circuit for the'coil 203 from the inner end of the coil 203 through wire 2, switch arm 209, contact 2I0, wire 2I2, a small number oi! turns of the coil 202, and wires 200 and 20I, back to the outer end of the coil 203. This shortcircuiting oi the coil 203 decreases the energization thereof and increases the energization of the coil 208, whereby the switch arm 2 I 5 is moved into engagement with the contact 2". Movement of the switch arm -2I5 into engagement with the contact 2 I 1 completes a circuit from the line wire 231, through wires 239 and 260, switch arm 2I5, contact 2", wire 263, limit switch contacts I64 and I66, wire 264, field winding I55 and wires 265 and 242 back to the other line wire 238. Completion of this circuit causes energization of the field winding I55 to move the crank 1I upwardly to lower the setting of the hydraulically operated pressure regulating valve 30 whereby the steam pressure within the header 28 is decreased to supply steam at a less pressure to the rumiing nozzles 23 and 55 whereby the pressure drop across the ejectors 32 and 60 is decreased.

Movement of the crank 1I upwardly in this manner causes right-hand movement of the slider I59 with respect to the balancing potentiometercoil I60, this right-hand movement causing, a partial short-circuit for the coil 202 which partial short-circuit is completed from the inner end of the coil 202 through wires 254 and 251, resistance 234, slider 235, wire 258, slider I59, the right-hand end of the balancing potentiometer coil I60, wires 248 and 244, protective resistance 243 and wire 200 back to the outer end of the coil 202. Completion of this partial shortcircuit decreases the energization of the coil 202 and increases the energization of the coil 201, it being remembered that the coil 202 was energized more than the coil 201 by the downward movement of the slider 81 with respect to the potentiometer coil 99. When the slider I59 has moved sufilciently far to the right with respect to the balancing potentiometer coil I60 so as to re-balance the energization of the coils 202 and 201 the switch am 209 is moved out of engagement with the contact 2 I 0 to the midposition shown in the drawings. This breaks the shortcircuit through the 2011103 causing equal ener-F gization oi the coils 203 and 208, which in turn causes movement of the switch arm 2l5 out of engagement with the contact 2" whereby the circuit through the field winding I55 is broken. This prevents further upward movement of the crank H and the hydraulically operated pressure regulating valve 30 is maintained at a setting in accordance with the temperature decrease in the condenser. 33. r

In this manner, the pressure drop across the orifices of the ejectors 32 and 60v are maintained constant regardless of the value of the vacuum e'xistingwithin the condenser 33, since steam at a higher pressure is supplied to the running nozzles 23 and 55. when the condenser vacuum decreases.

from the evaporators whereby the evaporator This constant pressure drop across the orifices entrains a constant amount of vapor vacuum is maintained constant under all conditions.

It will be noted that the circuits through the coils 203 and 208 of the relay 86 are completed through a small .number of turns of the coils 202 and 201, whereby the switch arm 209 is held forcibly in engagement with the contacts 210 or 2| I 'to prevent the occurrence of relay chatter. The protective resistances 243 and 250-are provided to prevent complete'short-circuiting ,of the coils 202 and 201 whereby burning outot the same is prevented. H Y

The range adjusting rheostat89 is provided in the circuits of the potentiometer coil 99 for raising or lowering the control point of controller 14. Movement of the sliders 232 and 233 simultaneously towards the right as viewed in Figure 2 decreases the resistance in series with the lower portion of the potentiometer coil 99 and increases the resistance in series with the upper portion of the potentiometer coil 99. This has the same effect as moving the slider 98 downwardly with respect to the coil 99. The motor 12 is operated to move the crank arm 1I upwardly to lower the pressure setting of the hydraulically operated pressure regulating valve 30 with respect to the temperature of the condensate within the condenser 33. Therefore, this right-hand movement of the sliders 232 and 233 lowers the pressure of the steam, admitted to the running nozzles 55 whereby the drop in pressure across the orifice of the ejectors 32 and 60 is decreased. Movement of the sliders 232 and 233 simultaneously to the left decreases the resistance in series with the upper portion of the potentiometer coil 99 and increases the resistance in series with the lower portion '01 the potentiometer coil 99. This has the same eflect as moving the slider 98 upwardly with respect to the coil 99 whereby the crank arm 19 is moved downwardly to raise the setting of the hydraulically operated pressure regulating valve whereby steam at a higher pressure is admitted to the running nozzles 55. This increases the drop pressures across the orifices oi the ejectors 32 and 60. Therefore, it is seen that by manually manipulating the range adjusting rheostat 89 the pressure drop across the orifices of the ejectors 32 and 60 may be adjusted at will to maintain desired values of vacuum in I the evaporators I0 and 42.

The diiferential adjusting rheostat 90 is utilized for adjusting the differential of operation of the controller "4. For a given movement of the slider 98 of the controller 14, a given moverespect to the resistance 234 requires a greater.

movement of the control slider 98 with respectto the potentiometer 99 to operate the motor 12 through a given'distance. Downward movement -of the slider 235 with respect to the resistance 234 increases the resistance in series with the balancing potentiometer whereby greater movement of the slider I59 with respect to the balancing potentiometer-coil I60 is required to rebalance the coils 202 and 201. It, therefore, follows that downward movement of the slider 235 with respect to the resistance 234 requires lesser movement of the control slider 96 with respect to its potentiometer coil 99 to move the motor 12 through a given distance. In this manner, the differential 'of the control system may be adjusted whereby the sensitivity of the control system may be selected to suit the operating characteristics of the refrigerating mechanism.

With the parts in the position shown in Figure 1, the main ejector mechanism is in operation and the valve I6 is in an open position whereby steam is being supplied to the running nozzles 23 to chill the cooling fluid in the main evaporator I0. The secondary refrigerating mechanism is not in operation and the evaporator 42 is disconnected from the condenser 33 by the valve 48 and the starting nozzles 54 and the running nozzles 55 are inoperative by reason of the valves 58 and 56 being closed. The main re-- frigerating mechanism is, therefore, providing all of the cooling. If the load on the main refrigerating mechanism should increase the temperature of the chilled cooling fluid within the evaporator I0 would likewise increase. This in crease in temperature of the evaporating fluid operates on the bulb 19 to move the mercury switch 96 to the position opposite to that shown in Figure 2. This' movement of the mercury switch 96 by the increased demand on the refrigerating mechanism completes a circuit from the line wire 231, through wires 261 and 268, the high temperature contacts of the mercury switch 96, Wire 269, contact I94, switch arm I92, wire 210, field winding I81 and wire 21I back to the other line wire 238. Completion of this circuit causes energization of the field winding I81 to start rotation of' the slider I16 of the program switch 84 in a clockwise direction. Energization of the field winding causes rotation of the cam I88 to move the switch arm I89 into engagement with the contact I90 to complete a maintaining circuit from the line wire 231, through wires'261 and 212, contact I90, switch arm I89, wire 213, field winding I81 and wire 21I back to the other line wire 238. This circuit maintains the field winding I81 energized until such time as the slider I16 of the program switch 84 is moved through at which time the'cam I 9I moves the switch arm I92 out of engagement with the contact I94 and into engagement with the contact I93 to break the starting circuit through the high temperature contacts of the mercury switch 96 and the switch arm I89 is moved out of engagement with the contact I90 to break the maintaining circuit through the field winding I81, whereby the slider I16 of the program switch 84 is maintained in a position removed from the position shown in the drawing by 180.

As pointed out above, the clockwise rotation of the slider I16 of the program switch 84 is relatively slow and when the slider I 16 moves into engagement with the conductor I10 a circuit is completed from the line wire 231, through wire 216, inside track I69, slider I16, conductor I10, wire 211, contact I43 of'motor 20, switch arm I4I, wire 218 and field winding I36 back to the other line wire 238. Completion of this circuit causes energization of the field winding I36 to start movement of the valve I9 towards a closed position. When the valve I9 has been so started in its closing movement the cam I31 moves the switch arm I38 into engagement with the contact I39 to complete a maintaining circuit from the line wire 231 through wire 211, contact I39, switch arm I38, wire 280 and field winding I36 back'to the other line wire 238. This insures complete closing movement of the valve I9 and when-the valve has been closed the switch arm I38 is moved out of engagement with the contact I 39 to break the circuit to the field winding I36 and the switch arm MI is moved into engagement with the contact I42 to place the motor in condition for opening movement. Closing of. the four-way valve I9 in this manner causes operation of the hydraulic motor I8 to move the gate I1 to close the valve I6, whereby communication between the main evaporator I0 and the condenser 33 is broken.

Further clockwise movement of the slider I18 into engagement with the conductor I1I completes a circuit from the line wire 231, through wire 216, inside track I69, slider I16, conductor I1I, wires 282 and 283, contact I28 of the motor- 59, switch arm I 21, wire 284 and field winding movement of the valve 58 is insured by a circuit from the line wire 231, through wire 285, contact I25, switch arm I24, wire 286 and field winding I22-back to the other line wire 238. This circuit through the 'field winding I22 is maintained until the valve 58 is moved to a complete open position at which time the switch arm I24 is moved out of engagement with the contact I25 and the switch arm I21 is moved into engagement with the contact I29. It is, therefore, seen that after the valve I 5 associated with the main evaporator I0 has been closed the valve 58 is opened, to supply steam to the starting nozzles 54 of the secondary ejector to produce a vacuum in the nozzle box 53.

Movement of the slider I16 into engagement with the conductor "I also completes a starting circuit from the conductor "I, through wires 282 and, 288, contact 224 ofthe relay 81, switch arm 220, wire 289, relay coil 2I9 and wire 290 back to the line wire 238. Completion of this circuit causes energization of the relay coil 2I9 to move the switch arms 220 and 22I into engagement with the contacts 222 and 223. Movement of the switch arm 220 into engagement with the contact 222 completes a maintaining circuit from the line wire 231, through wire 29I,

contact 229 of the relay, switch arm 228, wire 292, contact 222, switch arm 220, wire 289, relay coil 2I9 and wire 290 back to the other line wire Completion of this circuit maintains the relay coil 2I9 energized and maintains the switch arm 220 and 22I in engagement with the contacts 222 and 223, respectively.

Movement of the switch arm'22l out of engagement with the contact 225 breaks the circuit between the slider 98 of the controller 14 and the junction of the coils 202 and 201 whereby the controller 14 is rendered inoperative to control the proportioning motor 12 and consequently the hydraulically operated pressure regulating valve. Movement of the slider 22I into engagement with the contact 223 completes a short-circuit for the coil 202 of the relay 86 which circuit-may be traced from the inner end of the coil 202, through wires 254 and 255, switch arm 22I, contact 223, wires 249, 245 and 244, protective resistance 243 and wire 200 back to the outer end of the coil 202. This decreases the energization of the coil 202 and increases the energization of the coil 201 to cause downward movement of the crank 1|- of the motor 12 to increase the pressure setting of the hydraulically operated pressure regulating valve. Since the short-circuit of the coil 202 is substantially complete, complete downward movement of the crank H is brought about and, therefore, the pressure regulating valve is adjusted to its highest pressure setting whereby relatively high pressure steam is admitted in the steam header 28.

Further clockwise movement of the slider I16 into engagement with the conductor I12 completes a circuit from theline wire 231, through wire 216, inside track I69, a slider I16, conductor I12, wire 294, contact H4 of the motor 51, switch arm H3, wire 295 and field winding I08 back to the other line wire 238. This causes energization of the field winding I08 to move the valve 56 to its open position. Opening movement of the valve 56 is assured by a maintaining circuit completed from the line wire 231, through wire 296, contact III, switch arm H0, wire 291 and field winding I08 back to the other line wire 238. When the valve 56 is moved to its completely open position the switch arm H0 is moved out of engagement with the contact III to break the circuit through the field winding I08 and the switch arm H3 is moved into engagement with the contact H5. In this manner, the valve 56 is moved to anopen position whereby relatively high pressure steam from the regulated pressure header 28 is admitted to the running nozzles 55 to maintain the vacuum within the nozzle box 53.

Further clockwise movement of the slider I16 into engagement with the conductor I13 completes a circuit from the line wire 231 through wire 216, inside track I69, slider I16, conductor I13, wire 299, contact I29 of the motor 59, switch arm I21, wire 284 and field winding I22 back to the other line wire 238. This causesclosing movement of the valve 58 and closing movement of this valve is assured by means of the maintaining circuit outlined above. Closing of the valve 58 prevents the further supply of high pressure steam to the starting nozzles 54 of the secondary ejector. Further rotation of the slider I16 causes engagement thereof with the conductor I14 and, as pointed out above, the slider I16 is maintained in this position in contact with the conductor I14. A circuit is completed from the line wire 231 through wire 216, inside track I69, slider I16, conductor I14, wires 30I, 302 and 303 to the contact I42 of the motor 20, switch arm I, wire 218 and field winding I36, back to the other line wire 238. This causes energization of field winding I36 to move the valve I9 to an open position and the opening movement of this valve is assured by the maintaining circuit outlined above. Opening movement of the four-way valve. I9 causes operation of the hydraulic motor I8 to'move the valve I6 to open position whereby communication between the primary evaporator I0 and the condenser 33 is againestablished and the primary ejector mechanism is again placed in operation.

A circuit is also completed from the conductor I14 through wires 30I, 302 and 304, coil I of the solenoid 52 and wire 305 back to the other line wire 238. Completion of this circuit causes energization of the coil I45 to compress the spring I41 and to move the four-way valve 5| to an open position. Movement of the four-way valve 5| to the open position causes operation of the'hydraulic motor to move the valve 48 to open position to establish communication between the whereby the secondary ejector mechanism is of the relay coil 221 to move the switch arm 228 out of engagement with the contact 229 whereby the maintaining circuit for the relay coil 2I9 is broken and the switch arms 220 and 22I are moved outof engagement with the contacts 22I and 222, respectively, and into engagement with the contacts 224 and 225, respectively. Movement of the switch arm 22I out of engagement with the contact 223 breaks the short circuit through the coil 202 of the relay 86 to lower the setting of the hydraulically operated pressure regulating valve 30 and movement of the switch arm 22I into engagement with the contact 225 again places the relay 86 and, consequently, the motor 12 under the control of the temperature responsive controller 14 whereby the pressure of the steam within the header 28 is regulated in accordance with the temperature of the condensate within the condenser to maintain a constant pressure drop across the orifice of the ejectors 32 and 60 in the manner pointed out above.

Therefore, it is seen that normally the main refrigerating apparatus is in operation and that when the load on that refrigerating apparatus increases to such a value as to cause an increase in the chilled cooling water in the evaporator I0, the program switch 84 is placed in operation to perform a predetermined sequence of operation. First, the-valve I6 associated with the main evaporator I0 is moved to a closed position whereby the backing up of steam in the evaporator I0 is prevented. Secondly,'the valve 58 is opened to supply steam to the starting nozzles of the secondary ejector and the hydraulically operated pressure regulating valve 30 is adjusted to its highest pressure setting whereby steam at relatively high pressure is admitted to the steam header 28. Thirdly, the valve 56 is moved to an open position whereby this high pressure steam in the regulated pressure steam header 28 is admitted'to the running nozzles of the secondary ejector. Fourthly, the valve 58 is moved to a closed position shutting off the supply of steam to the starting nozzles 54 of the secondary ejector. Fifthly, the valve I6 is opened and communication between the main evaporator I0 and the condenser 33 is re-established, the valve 48 is opened and communication between the secondary evaporator 42 and the condenser 33 is established, and the control of the hydraulically operated pressure regulating valve is returned to the temperature responsive controller 14 whereby the pressure in the regulated steam header 28 is decreased and the pressures therein are regulated in accordance with the temperature of the condensate within the condenser 33. Inthis manner, both the main ejector and the secondary ejector are placed in operation to supply sufiicient cooling to make up tor the increased load on the refrigerating mechanism.

When the load on the refrigerating mechanism decreases the temperature of the chilled water within the main evaporator I0 will also decrease and when the temperature of this chilled water 'has decreased to a given value the mercury switch 96 of the temperature responsive controller 11 is tilted to the position shown in the drawings whereby contact between the low temperature contacts is established. This causes completion of a circuit from the line wire 231, through wires 261 and 268, the low temperature contacts of the mercury switch 96, wire 214, contact 93, switch arm I92, wire 210, fleld winding I81 and wire 21I back to the other line wire 238. Completion of this circuit causes another 180 rotation of the slider I16 of the program switch 84. Complete movement of the slider I16 through 180 to the position shown in Figure 2 is assured by the maintaining circuit outlined above.

Movement of the slider I16 out of engagement with the contact I14 breaks the circuit through the relay coil 211 of the relay 88, whereby the switch arm 228 is moved into engagement with the contact 229 but since the maintaining circuit through the relay coil 2I9 of the relay 81 was previously broken the relay coil 2I9 may not again be energized until such time as the slider I I16 moves into engagement with the conductor I1I upon a demand for more cooling. Movement of the slider I 16 out of engagement with the conductor I14 also breaks the circuit through the coil I45 of the solenoid 52, whereby the compression spring I41 causes the valve 6| to be moved to a closed position. This closing movement of the valve 5I causes operation of the hydraulic motor 50 to move the valve 48 to a closed position breaking communication between the secondary evaporator 42 and the condenser 33.

Movement of the slider I16 into engagement with the conductor I15 completes a circuit from the line wire 231, through wire 216, inside track I69, slider I16, conductor I15, wire 309, contact II5, switch arm II3, wire 285 and field winding I08 back to the other line'wire 238. Completion of this circuit causes energization of the field winding I08 to move the valve 56 to a closed position, closing movement of the valve being assured by the maintaining circuit outlined above. 7

slider I16 continues to move in a clockwise direc-- tion until it has completed 180 of rotation at which time it comes tb rest in the position shown in Figure 2.

From the above, it is seen that when the load on the refrigerating mechanism asa whole decreases so as to not require the operation of the secondary refrigerating mechanism, this secondary refrigerating mechanism is placed out of operation in the following steps: First, the valve 48 is moved to a closed position breaking communication between the secondary evaporator 42 and the condenser 33 and, secondly, the supply of steam to the running nozzles 55 of the secondary evaporator is shut off. The main refrigerating mechanism remains in operation to supply the necessary cooling at this particular load requirement. Upon an increase in load the sequence of operation outlined above will again be followed and the secondary refrigerating mechanism will again be placed in operation.

A primary 3I2 of a step-down transformer 3 having a secondary 3I3 is connected across the line wires 231 and 238. If the load on the refrigerating mechanism should decrease so that no Conswitch I02 to a circuit making position to com plete a circuit from one end of the secondary 3I3, through wire 3| 4, mercury switch I02, wire 3I5, signal or alarm 9| and wire 3I6 back to the other end of the secondary 3I3. Completion of this circuit causes operation of the alarm 9| to indicate to the engineer in charge of the refrigerating mechanism'that no more cooling is required and'that the main ejector mechanism should be closed down. In order to close down the main refrigerating mechanism all that is required is closure of the manually operated valve 29 whereby the supply of steam to the running nozzles 23 is shutoff.

Although I have shownthe temperature responsive controller 14 tobe responsive to the temperature of the condensate of the condenser 33 for the purpose of maintaining a constant pressure drop across the ejectors regardless of the .vacuum existing within the condensers, other ture responsive controller 14 could respond to the temperature of the discharge condensing fluid, or in case a cooling tower is used the controller 14 could respond to the temperature of the condensing fluid flowing from the cooling tower to the condenser.

Although I have shown one form of my invention for purposes of illustration, other forms thereof may become apparent to those skilled in the art and, consequently, this invention is to be limited only by the scope of the appended claims and the prior art.

I claim as my invention:

1. In a refrigerating system having a source of steam, an evaporator, anejector and a condenser,

the combination of means responsive to a call for cooling for supplying steam at a high pressure to the ejector for a period of time for placing the refrigerating system in operation and then supplying steam at a reduced pressure to the ejector for maintaining the refrigerating system in operation, and means for regulating the supply of steam at the reduced pressure to maintain the pressure drop across the ejector constant.

2. In a refrigerating system having a source of steam, an evaporator, a condenser and an ejec-- tor, the combination of means responsive to the temperature of the chilled cooling fluid in the evaporator, a program switch controlled by said temperature responsive means, means for supplying steam at high pressures and at reduced pressures to the ejector, said means being controlled by said program switch, the arrangement being such that upon an increase in chilled cooling fluid temperature steam is supplied to the ejector at high pressurefor an interval of time to place the refrigerating system in operation-and then at a .reduced pressure to maintain the refrigerating system in operation.

3. In a refrigerating system having a source of steam, an evaporator, a condenser and an ejector, the combination of means responsive to the temperature of chilled cooling fluid in the evaporator, a program switch controlled by said temperature responsive means, means for supplying steam at high pressures and at reduced pressures to the ejector, said means being controlled by said program switch, the arrangement being such that upon an increase in chilled cooling fluid temperature steam is supplied to the ejector at high pressure for an interval of time to place the refrigerating system in operation and then at a reduced pressure to maintain the refrigerating system in operation, pressure regulating means for maintaining the supply of steam at a constant reduced pressure, and means responsive to a condition in the condenser for adjusting said pressure regulating means to maintain the pressure drop across the ejector constant regardless of fluctuations in condenser vacuum.

4. In a refrigerating system having an evaporator, an ejector, a steam supply and a condenser,

,the combination of a first valve means between the evaporator and the ejector, a second valve means for controlling the supply of steam to the ejector, a pressure regulating valve means for maintaining the steam pressure constant, adjusting means for the pressure regulating valve, and means responsive to a call for cooling, first, for operating the adjusting means to adjust the pressure regulating valve means to supply high pressure steam, second, for opening the second valve means to supply steam at high pressure to the ejector, and third, for operating the adjusting means to allow normal presure regulation of the steam supply at a reduced pressure and for opening the first valve means.

5. In a refrigerating system havingan evaporator, an ejector, a steam supply and a condenser,

the combination of a first valve means between constant.

the evaporator and the ejector, a second valve means for controlling the supply of steam to the ejector, a pressure regulating valve means for maintaining the steam pressure constant, adjusting means for the pressure regulating valve,

means responsive to a call for cooling, first, for

operating the adjusting means to adjust the pressure regulating valve means to supply high pressure steam, second, for opening the second valve means to supply steam at high pressure to the ejector and, third, for operating the adjusting means to allow normal pressure regulation of the steam supply at a reduced pressure and for opening the first valve means, and means for adjusting the pressure reglating valve means in accordance with a condition in the condenser to maintain the pressure drop across the ejector 6. In a refrigerating system having an evaporator, an ejector, a steam supply and a condenser, the combination of starting and running nozzles for the ejector, first valve means controlling communication between the evaporator and the ejector, second valve means for controlling the supply of high presure steam to the starting nozzles, third valve means for controlling the supply of steam to the running nozzles, pressure regulating means controlling the pressure of the steam controlled by the third valve means, adjusting means for the pressure regulating means, and means responsive to a demand for cooling, first for opening the second valve means to admit high pressure steam to the starting nozzles and for.

operating v the adjusting means to admit high pressure steam to the third valve means, second, for opening the third valve means to admit high pressure steam to the running nozzles, third, for closing the second valve means, and fourth, for opening the first valve to communicate the evaporator with the ejector and for operating the ad- 'justing means to admit steam to the running nozzles at a reduced constant pressure.

'7. In a refrigerating system having an evaporator, an ejector, a steam supply and a condenser, the combination of starting and running nozzles for the ejector, first valve means controlling communication between the evaporator and the ejector, second valve means for controlling the supply of high pressure steam to the starting nozzles, third valve means for controlling the supply of steam to the running nozzles, pressure regulating means controlling the pressure of the steam controlled by the third valve means,

adjusting means for the pressure regulating means, means responsive to a demand for cooling, first, for opening the second valve means to admit high pressure steam to the starting nozzles and for operating the adjusting means to admit high pressure steam to the third valve means, second,

for opening the third valve means to admit high pressure steam to the running nozzles, third, for

closing the second valve means, and fourth. for.

opening the first valve to communicate the evaporator with the ejector and for operating the adjusting means to admit steam to the running nozzles at a reduced constant pressure, and means responsive to a condition in the condenser for controlling the adjusting means to regulate the steam supplied to the running nozzles in accordance with condenser vacuum.

8. In a refrigerating system having a steam supply, a condenser, primary and secondary ejectors and primary and secondary evaporators, first valve means controlling communication between the primary ejector and the primary evaporator, second valve means controlling communication between the secondary ejector and the ating the adjusting means to raise the setting of the pressure regulating means, third, for opening the third valve means to admit high pressure steam to the secondary ejector, and fourth,

for opening the first and second valve means and for operating the adjusting means to lower the setting of the pressure regulating means.

9. In a refrigerating system having a steam supply, a condenser, primary and secondary ejectors and primary and secondary evaporators, first valve'means controlling communication between the primary ejector and the primary evaporator, second valve means controlling communication between the secondary ejector and the secondary evaporator, pressure regulating means for controlling the supply of steam to the primary and secondary eje'ctors, adjusting means for the pressure regulating means, third valve means for additionally. controlling the supply of steam to the secondary ejector, means respon-- sive to an increase in temperature of the chilled cooling fluid in the primary evaporator for, first, closing the .first valve means, second, for operating the adjusting means to raise the setting of the pressure regulating means, third, for opening the third valve means to admit high pressure steam to the secondary ejector, and fourth, for opening the first and second valve means and for operating the adjusting means to lower the setting of the pressure regulating means, and means responsive to a condition in the condenser for controlling the adjusting means to regulate the steam supplied to the primary and secondary ejectors in accordance with condenser vacuum.

10; In a refrigerating system having a source of steam, an evaporator, an ejector and a condenser, the combination of a valve for controlling the supply of steam to the ejector, means responsive to steam pressure down stream of the valve, means responsive to the vacuum in the condenser, means responsive to a demand for cooling, and means controlled by said steam pressure responsive means, said vacuum responsive means and said cooling demand responsive means for operating said valve for a period of time to deliver steam at a relatively high pressure to the ejector and for subsequently operating said valve to deliver steam at a reduced constant pressure which is adjusted in accordance with condenser vacuum.

11. In a refrigerating system having a source of steam, an evaporator, an ejector and a condenser, the combination of valve means for controlling the supply of steam to the ejector, a.

pressure regulating valve means for maintaining the steampressure constant, adjusting means for the pressure regulating valve, and means responsive to a call for cooling, first, for operating the adjusting means to adjust the pressure regulating valve means to supply high pressure steam, second, for opening the valve means to supply steam at high pressure to the ejector and, third, for operating the adjusting means to allow normal pressure regulation of the steam supply at a reduced pressure.

12. In a refrigerating system having a source of steam, an evaporator, an ejector and a condenser, the combination of valve means for controlling the supply of steam to the ejector, a pressure regulating valve means for maintaining the steam pressure constant, adjusting means for the pressure regulating valve, and means responsive to a call for cooling, first, for operating the adjusting means to adjust the pressure regulating valve means to supply high pressure steam,

' second, foropening the valve means to supply steam at high pressure to the ejector and, third, for operating the adjusting means to allow normal pressure regulation of the steam supply at a reduced pressure, and. means for adjusting the pressure regulating valve means in accordance with a condition in the condenser to maintain the pressure drop across the ejector constant.

ling the supply of steam to the running nozzles,

pressure regulating valve means controlling the pressure of the steam controlled by the second valve means, adjusting means for the pressure regulating means, and means responsive to a demand for cooling, first, for opening the first valve means to admit high pressure steam to the starting nozzles and for operating the adjusting means to admit high pressure steam to the second valve means, second, for opening the second valve means to admit high pressure steam to the running nozzles, third, for closing the first valve means, and fourth, for operating the adjusting means to admit steam to the running nozzles at a reduced constant pressure.

14. In a refrigerating system having a source of steam, an evaporator, an ejector and a condenser, the combinaiton of starting and running I nozzles for the ejector, first valve means for controlling the supply of high pressure steam to the starting nozzles, second valve means for'controlling the supply of steam to the running nozzles,

pressure regulating valve means controlling the pressure of the steam controlled by the second valve means, adjusting means for the pressure regulating means, means responsive to a demand for cooling, first, for opening the first valve means to admit high pressure steam to the starting nozzles and for operating the adjusting means to admit high pressure steam to the second valve means, second, for opening the second valve means to admit high pressure steam to the rimning nozzles, third, for closing the first valve means, and fourth, for operating the adjusting ,means to admit steam to the running nozzles at a reduced constant pressure, and means responsive to a condition in the condenser for controlling the adjusting means to regulate the steam supplied to the running nozzles in accordance with condenser vacuum.

15. In a refrigerating system having a source of steam, an evaporator, an ejector and a condenser, the combination of means .for supplying steam to the ejector at a high pressure for a predetermined period of time in response to a call for cooling for placing the refrigerating system in operation, and means for subsequently supplying steam to the ejector at a reduced pressure for maintaining the refrigerating system in operation.

' 16. In a refrigerating system having a source of steam, an evaporator, a condenser and an ejector, said ejector including a plurality of noz zles, a starting valve means in control of the supply of steam to said nozzles, a running valve means in control of the supply of steam to said nozzles, a thirdvalve means controlling communication between the evaporator and the ejector, a program switch means, an electric motor controlling the operation of said switch means, means responsive to a rise in temperature of the chilled cooling fluid in the evaporator to a'predetermined value to energize said motor to cause operation of said program switch means, circuit connections controlled by said program switch means to cause the opening of the starting valve means, followed by the opening of the running. valve means, and to subsequently cause opening of the third valve means and closure of the starting valve means, said motor again causing operation of said program switch means in response to a drop in temperature of the chilled cooling fluid in the evaporator to ,a predetermined value, and circuit connections operated by this last operation of the program switch means to cause the closure of said running valve means and the third valve means.

17. In a refrigerating system having a source of steam, an evaporator, a condenser and an ejector, said ejector including a plurality of nozzles, a starting valve means in control of the supply of steam to said nozzles, a running valve means in control of the supply-of steam to said program switch means to first cause the opening of the starting valve means, to then cause the opening of the running valve means, to subsequently cause opening of the third valve means by means of the hydraulic motor means and closure of the starting valve means, said motor again causing operation of the program switch means in response to a drop in temperature of operated by this last operation of the program switch means to cause the hydraulic motor means to move the third valve means to closed position 5 and to cause closure of the running valve means.

JOHN E. HAINES. 

